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AT88SC6416C

5015BS–SMEM–04/03

Protocol Selection

The AT88SC6416C supports two different communication protocols.

•

Smart Card Applications: The asynchronous T = 0 protocol defined by ISO 7816-3

is used for compatibility with the industry’s standard smart card readers.

•

Embedded Applications: A 2-wire serial interface is used for fast and efficient

communication with logic or controllers.

The power-up sequence determines which of the two communication protocols will be

used.

Asynchronous

T = 0 Protocol

This power-up sequence complies with ISO 7816-3 for a cold reset in smart card

applications.

•V

•

Set I/O-SDA in receive mode.

•

Provide a clock signal to CLK-SCL.

•

RST goes high after 400 clock cycles.

The device will respond with a 64-bit ATR code, including historical bytes to indicate the

memory density within the CryptoMemory family. Once the asynchronous mode has

been selected, it is not possible to switch to the synchronous mode without powering off

the device.

Figure 2. Asynchronous T = 0 Protocol

After a successful ATR, the Protocol and Parameter Selection (PPS) protocol, as defined

by ISO 7816-3, may be used to negotiate the communications speed with CryptoMemory

devices 32 Kbits and larger. CryptoMemory supports D values of 1, 2, 4, 8, 12, and 16 for

an F value of 372. Also supported are D values of 8 and 16 for F = 512. This allows selec-

tion of 8 communications speeds ranging from 9600 baud to 153,600 baud.

Synchronous

2-wire Serial Interface

The synchronous mode is the default after powering up V

on RST. For embedded applications using CryptoMemory in standard plastic packages,

this is the only communication protocol.

•

Power-up V

•

After stable V

Figure 3. Synchronous 2-wire Protocoll

Note:

Five clock pulses must be sent before the first command is issued.

Vcc

I/O-SDA

RST

CLK-SCL

ATR

Vcc

I/O-SDA

RST

CLK-SCL

1

2

3

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